Question

A solution is prepared by addition of excess of $AgN{O}_3$ solution in KI solution. The charge likely to develop on colloidal particles is?

• A. Positive
• B. Negative
• C. No charge
• D. Both charges

Answer 1

The correct option is A Positive

When $AgN{O}_3$ is added to a $KI$

$KI$ + $AgN{O}_3$ $\left(excess\right)$ → $AgI$ + $KN{O}_3$

In the above reaction since $AgN{O}_3$ is added to the solution of $KI$ ,I assume that $AgN{O}_3$ is added in excess. Now after the formation of the collide $\left(AgI\right)$ , the excess ions ($Ag+$, $N{O}_3^{-}$), will tend to adsorb on the surface of the colloid. When it comes to the question of which ion absorbs, we need to understand the concept of preferential adsorption of common ions ( common in colloid and in the medium). Thus since $Ag+$ is common, it adsorbs on the surface of the colloid and makes the colloid,

POSITIVE